Among the tRNA population of the archaeal parasite Nanoarchaeum equitans are five species assembled from separate 5 and 3 tRNA halves and four species derived from tRNA precursors containing introns. In both groups an intervening sequence element must be removed during tRNA maturation. A bulge-helixbulge (BHB) motif is the hallmark structure required by the archaeal splicing endonuclease for recognition and excision of all introns. BHB motifs are recognizable at the joining sites of all five noncontinuous tRNA species, although deviations from the canonical BHB motif are clearly present in at least two of them. Here, we show that the N. equitans splicing endonuclease cleaves tRNA precursors containing normal introns, as well as all five noncontinuous precursor tRNAs, at the predicted splice sites, indicating the enzyme's dual role in the removal of tRNA introns and processing of tRNA halves to be joined in trans. The cleavage activity on a set of synthetic canonical and noncanonical BHB constructs showed that the N. equitans splicing endonuclease accepts a broader range of substrates than the homodimeric Archaeoglobus fulgidus enzyme. In contrast to the A. fulgidus endonuclease, the N. equitans splicing enzyme possesses two different subunits. This heteromeric endonuclease type, found in N. equitans, in all Crenarchaeota, and in Methanopyrus kandleri, is able to act on the noncanonical tRNA introns present only in these organisms, which suggests coevolution of enzyme and substrate. tRNA processing M any tRNA genes in Eukarya and Archaea contain intron sequences that must be removed during tRNA processing to generate mature, functional tRNAs. The first step of tRNA splicing is catalyzed by a specific endonuclease that excises the intron from the precursor tRNA (pre-tRNA), yielding two tRNA half-molecules, a 5Ј half-exon ending with a 2Ј,3Ј-cyclic phosphate, and a 3Ј half-exon with a 5Ј-hydroxyl terminus (1, 2). This step is followed by the joining of the tRNA exons catalyzed by a tRNA splicing-specific ligase in Eukarya; however, little is known about the tRNA ligation mechanism in Archaea (3). The archaeal splicing endonuclease recognizes a consensus bulgehelix-bulge (BHB) structure that is found at the intron-exon junctions of intron-containing tRNA (4), rRNA (5, 6), and mRNA (7). The BHB motif exhibits pseudo-twofold symmetry with the two 3-nt bulges present on the same minor groove face of the central 4-bp helix, termed the 3-4-3 BHB (8). This structure makes the splice sites well positioned for attack by the splicing endonuclease. Two archaeal endonuclease families are found in Euryarchaeota: (i) ␣ 2 homodimeric enzymes of 288-353 aa in length or (ii) ␣ 4 homotetrameric enzymes of Ͻ200 aa in length (1, 9). These endonucleases seem to have a strict requirement for the pseudosymmetric 3-4-3 BHB RNA (4). Recently, a third family of splicing endonucleases was discovered in the Crenarchaeon Sulfolobus solfataricus; the enzyme has a heteromeric subunit composition (10). Multiple sequence alignments and BLAST searc...

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Although many of the surgical and technological advances for prosthetics have emerged from caring for adults, the pediatric patient with limb differences continues to provide unique challenges and demands appropriate, pediatric-specific innovation. Not only do children test the current technology with their size, weight, and potential growth, but also with their chosen activities, energy-level and drive to explore varied environments. This article explores the recent advances within the broader realm of prosthetics, primarily based on research in adult patients.  It identifies technologies that have already been translated to pediatric populations and points out areas for potential pediatric applications. This review also highlights numerous needs and gaps in the currently available resources and tools for these patients, including surgical techniques, prosthetic componentry, and rehabilitation strategies. Further innovation and research are needed for pediatric patients to maximize their functional potential while using a prosthesis.

As the growth of online education offered by universities accelerates and spreads, universities are increasingly grappling with concerns related to widespread availability and the maintenance of academic quality. The Quality Matters at Southeastern Program fosters quality through a peer review process and offers a certification process to help assure quality in the Universitys online and blended course offerings. This report is a look at perceived impacts of the internal certification process by faculty.